Gas operated blast valve for double-flow interrupters

ABSTRACT

A compressed gas circuit interrupter of the dual pressure type in which one or more pair of contacts are separated in a high pressure gaseous environment, and the high pressure gas exhausts through both of the separable contacts. For each pair of contacts the continued exhaust of gas through the contacts is controlled by a mechanically operated main blast valve and a gas operated auxiliary blast valve. The auxiliary blast valve works in conjunction with the main blast valve and utilizes primarily the internal gas pressure for its operating power and control.

United States Patent [1 1 Cromer et'al.

[ Feb. 12, 1974 GAS OPERATED BLAST VALVE FOR DOUBLE-FLOW INTERRUPTERS Inventors: Charles E. Cromer, Trafford; Kue

Hong Yoon, Pittsburgh; Hayes 0. Dakin, Jr., Irwin, all of Pa.

Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed: July 7, 1972 Appl. No.: 269,691

Assignee:

US. Cl. 200/148 B, 200/148 BV Int. Cl. H0lh 33/54 Field of Search 200/148 B, 148 BV, 148 R References Cited UNITED STATES PATENTS 8/1972 Fawdrey et al 200/148 B 3,686,454 8/1972 Berkebile 200/148 BV Primary Examiner-Robert S. Macon Attorney, Agent, or Firm-l-l. G. Massung 5 7 ABSTRACT A compressed gas circuit interrupter of the dual pressure type in which one or more pair of contacts are separated in a high pressure gaseous environment, and the high pressure gas exhausts through both of the separable contacts. For each pair of contacts the continued exhaust of gas through the contacts is controlled by a mechanically operated main blast valve and a gas operated auxiliary blast valve. The auxiliary blast valve works in conjunction with the main blast Y valve and utilizes primarily the internal gas pressure for its operating power and control.

9 Claims, 8 Drawing Figures (230 PSI) FOR PATENTEU l 2 3.782, 2 l 8 sum 2 BF 5 LOW PRESSURE (60 PSI) FOR EXAMPLE HIGH PRESSURE EXAMPLE HIGH PRESSURE (230 PSI) FOR EXAMPLE GAS OPERATED BLAST VALVE FOR DOUBLE-FLOW INTERRUPTERS BACKGROUND OF THE INVENTION This invention relates to a compressed gas circuit interrupter of the dual pressure type, in which one or more pairs of contacts are separated in a high pressure gaseous environment and the high pressure gas exhausts through both of the separated contacts. More particularly the present invention relates to the downstream blastvalves which control the continued exhaust of relatively high pressure gas through the separable contact structure.

In prior art compressed gas circuit interrupters of the dual pressure type, as described in detail in US. Pat. No. 3,596,028 issued July 27, 1971 to Richard E. Kane et al. and assigned to the same assignee as the present application, a high pressure gas, which aids in extinguishing the arc, surrounds the contact structure. During circuit interruption, the contacts separate and an arc is formed therebetween. To help interrupt this are the high pressure gas immediately available at the separable contact structure passes through the interior of one or both of the separable contacts and is controlled by one or more downstream blast valves. The downstream blast valves are mechanically controlled by the movable contact structure. Circuit interruption and blast valve movement is accomplished by a pneumatic operator at the top of the arc extinguishing assembly. The pneumatic operator is controlled by a three-way tripping device which itself is controlled by an insulating operating rod extending downwardly interiorly of the interrupter to a ground potential operating mechanism. The output force of the pneumatic operator, and the complexity of mechanically interconnecting the blast valves, limits the number of blast valves which the pneumatic operator can control. Due to these limitations not all contact structures utilize gas flow through the interior of both of the separable contacts. In some instances, contact structures which utilize gas flow through only one of the separable contacts are used.

SUMMARY OF THE INVENTION The interrupting capability of gas blast interrupters can be greatly increased by providing for gas passage through the interior of both of the separable contacts. When the insulating gas can flow through the interior of both of the interrupter contact nozzles this is referred to as double flow interruption, as opposed to single flow interruption when the high pressure gas can flow through only one of the contacts. This invention discloses a means for providing a double flow interrupter, by using a mechanically operated main blast valve, which is connected to the pneumatic operator as in prior art applications, and a gas operated auxiliary blast valve, which operates from the internal gas pressure and is not mechanically connected to the pneumatic operator. Double flow interruption is accomplished without mechanically coupling the auxiliary blast valve to the contact driving mechanism and thus avoiding additional loading of the pneumatic operating mechanism. Thus, double flow interruption is attained with the same operating mechanism which is used on prior art applications, for single flow interruption. The operating mechanism can be used without redesign, without additional mechanical connections or addition] mechanism cost. Thus apparatus which is presently using single flow interruption can be converted to double flow interruption to increase interrupter capability without altering the pneumatic operator mechanism or the mechanically operated main blast valve.

On contact opening, during circuit interruption, a means is provided for closing the gas operated auxiliary blast valve after the interrupting function is completed. On a contact closing operation, means are provided for opening the gas operated auxiliary blast valve and the main blast valve, after the contacts have closed, thus providing a system in which full differential pressure exist across the interrupted contacts on initial contact parting. When the contacts are in the closed position, high pressure gas, in a chamber of the gs operated auxiliary blast valve, forces the blast valve to the open position. During circuit interruption, as the main contacts part, high pressure gas flows through the inside of the contacts, to accomplish circuit interruption. This high pessure gas also flows through metering holes, in one of the contact assemblies, into a first chamber of the auxiliary blast valve to start closing the auxiliary blast valve. The time delay from contact opening until the auxiliary blast valve starts to close can be determined by the flow through the metering holes. As the auxiliary blast valve continues to close high pressure gas comes in contact with additional areas of the auxiliary blast valve, increasing the closing force on the auxiliary blast valve and slamming the valve to the closed position. A sliding portion of the auxiliary blast valve closes against a resilient seat, which provides a gas tight seal between the high pressure gas inside the contact and the low pressure gas chamber.

During a closing operation as the contacts close the main blast valve, after a fixed time delay, is opened discharging the high pressure gas within the contacts into the low pressure chamber. WHen the pressure inside of the contacts which drives the gas operated auxiliary blast valve closed falls below a critical level, the force tending to hold the auxiliary blast valve closed is exceeded by the opening force provided by the high pressure gas in a second chamber of the auxiliary blast valve. The auxiliary blast valve then moves rapidly to its fully open position.

The present invention has the advantage of providing for double flow interruption without mechanical connection to the operating means and without redesign of the operating means or the main blast valve assembly of prior art single flow interrupters.

BRIEF DESCRIPTION OF THE DRAWINGS Other advantages of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an end elevation view of a compressed gas dual pressure type circuit interrupter embodying the principles of the present invention;

FIG. 2 is an enlarged vertical section view taken through a portion of the interrupter shown in FIG. 1 illustrating the pneumatic operating assembly;

FIG. 3 is an enlarged vertical section view of a portion of the interrupter shown in FIG. 1 illustrating a contact assembly embodying the teachings of the present invention;

FIG. 4 is a sectional view of a portion of an interrupter which has two contact assemblies for double break, double flow operation;

FIG. 5 is a sectional view of a portion of an auxiliary gas operated blast valve in the closed position;

FIG. 6 is a view similar to FIG. 5 with the gas operated blast valve in an intermediate position;

FIG. 7 is a view similar to FIG. 5 with the gas operated auxiliary blast valve in the opened position; and

FIG. 8 is a schematic view of a circuit breaker comprising two interrupters, one interrupter is of the single break construction, and the other interrupter is of the double break construction.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and more particularly to FIG. 1 there is shown a compressed gas dual pressure type circuit interrupter or breaker 12. The circuit breaker 12 is supported by a metallic framework composed of suitable structural members 14 such as angle iron, braces, channels, I-beams or I-I-beams. The circuit breaker 12 is of the dual pressure type involving the use of a suitable arc extinguishing gas, such as sulfurhexafluoride, SF6, at two different pressures, such as a high pressure of approximately 230 psi, suitable for extinguishing an arc formed during circuit interruption, and a low pressure of approximately 60 psi. The dual pressure circuit breaker 12 comprises three portions, an interrupter' or arc extinguishing portion 15, a grounded housing 26, and a terminal bushing structure 28, which are assembled into a generally U-shaped structure as can best be seen in FIG. 1. When more breaks are required in the circuit than can be supplied with the standard circuit breaker 12 as shown in FIG. 1, the terminal bushing structure 28 can be replaced with an interrupter assembly 15 for additional circuit breaks, as

may be used as the are extinguishing gas and also as an insulating gas to enable a close spacing of the energized, or the live parts. This insulating gas is also used within the terminal bushing structure 28 as described in detail in US. Pat. No. 2,757,261. The terminal bushing structure 28 comprises an axially extending high voltage terminal stud 29, having a threaded upper end 31. Surrounding the terminal stud 29, in spaced relation therewith, is an outer weather-proof insulating shell or casing 30 having a plurality of weather sheds 32 for increased surface creepage distance. Although the gas pressure in the lower U-shaped bend 71 is of a high pressure, of approximately 230 psi, it is desirable to reduce the pressure acting internally upon the weatherproof casing 30 to approximately 25 psi. This may be accomplished by a pressure reducing valve (not shown) interconnecting the high pressure space in the U- shaped bend 71 with the interior space of the weatherproof casing 30. A frusto-conical insulating support member 119 is used to provide a barrier between the high pressure region in the U-shaped bend 71 and the relatively low pressure region internal to the weather casing 30. y

The lower end of the weather casing 30 may have an annular flange 120 secured thereto, which in turn may be bolted by a plurality of circumferentially spaced bolts to. the supporting flange 121. The supporting flange 121 is in turn welded or otherwise secured to the upper tubular portion 122 of the lower U-shaped high pressure reservoir 71.

For the measurement of current passing through the circuit breaker 12 one or more current transformers (CT s) 72 may be utilized surrounding the high pressure U-shaped reservoir 71. Conducting stud 29, of terminal bushing 28, at its lower end connects to a U- shaped conductor 27, which runs internal to the U- shaped high pressure reservoir 71. The U-shaped conductor 27 carries the load current. The high pressure U-shaped reservoir 71 contains gas at a high pressure, of approximately 230 psi, and is comprised of three flanged tubular portions 73, 74 and 122. Flanged portions 73, 74 and 122 are bolted together with gaskets interposed therebetween and surrounding the inner U- shaped conductor 27, which is at a high voltage during normal circuit breaker operation. This construction not only provides a U-shaped high pressure reservoir 71 for admittance of high pressure gas upward into the space 47 of interrupter 15, external of contact structure 20 of interrupter 15, but also due to the high pressure insulating characteristics of the gas permits the close spacing between the inner high voltage conducting U-shaped stud 27 and the grounded U-shaped casings 73, 74 and 122. In addition this construction provides a compact apparatus with ready accessibility provided for maintenance operations, when required. Since sulfurhexafluoride, SP6, gas at a pressure of 230 psi liquefies at about 50F, band type heaters 75 are connected around the U-shaped reservoir 71 to keep the gas temperature above approximately, 75F. The high convection heat transfer coefficient of the insulating gas at the pressure of 230 psi insures almost constant temperature throughout the high pressure reservoir in the U-bend 71 of the breaker 12. No heating is required in the lower pressure areas as liquefaction at these pressures occurs well below the minimum operating temperature.

A control trip rod 13 extends from the grounded housing 26 upward into the top of the arc extinguishing assembly 15 and operates the three-way control valve 36. Referring now to FIG. 2 of the drawings, there is shown a sectional view of the upper end of the interrupter 15. The upper end of the valve control trip rod 13 is biased upward by a battery of compression springs 131 seating upon a spring seat 132 affixed to the valve control rod 13, or an extension thereof, as at 34. The compression spring 131 serves to bias a pressure balanced three-way control valve 36 to its upper closed position. To effect an opening operation of circuit breaker 12 the valve control rod 13 is moved upward approximately of an inch so as to permit the admission of high pressure gas existing within region 37, lipwardly through a conduit 39 and across the entire lower surface of the dual acting piston structure 108. Dual acting piston structure 108 is connected by means of a piston rod 41 and other mechanical lingakes to the movable contact 21, of the contact assembly 20. The piston structure 108 is mechanically tied by means of the piston rod 41 to a generally ladder-shaped structure 43. The dual acting piston 108 has differential annular areas for opening and closing the contact structure 20.

To effect an opening operation of the interrupter 15, actuation of the three-way control valve 36 is brought about by an upward motion of the valve control tripping rod 13. The control valve 36 then admits high pressure gas upon the lower face 109 of the piston structure 108, thereby causing upward motion of piston structure 108 and the movable contact 21. As the pis- .piston structure 108 the check valve 54 rises and permits high pressure gas, which is constantly present within the region 56, to flow past the ring-shaped check valve 54 and into the shock absorbing region 51. During closing a stepped portion 110, of the movable piston 108, moves into the space 58 which contains gas of relatively high pressure. Movement of stepped portion 110 into space 58 performs a shock absorbing function during closing stroke, the gas trapped. in space 58 leaks through perforations provided in a ring-shaped check valve 60.

. Fixedly attached to the piston structure 108 and in effect constituting an extension of the piston rod 41 is an indicator stem 62, which carries a green flag 63. The green flag 63 projects upwardly into a transparent cap 64 provided at the upper end of the interrupter 15. The green flag 63 clearly indicates in a positive manner the fact that the circuit breaker 12 has its contact structure in the fully open position.

To take care of the situation where a low ambient temperature may be encountered and liquefaction of the high pressure sulfurhexafluoride gas results, liquid drain pipes 69 and 70 are provided. The liquid will flow downward by gravity through pipes 69 and 70 into the high pressure reservoir within the arc interrupter 15 and then into the lower U-shaped bend 71 where suitable heaters 75 are located to vaporize any liquified gas. Y

As can best be seen in FIG. 3, the movable contact 21 is mechanically connected to the ladder-shaped member 43, which in turn is mechanically adjustably secured to the lower end of piston rod 41. A pair of spaced insulating operating rods 44 extend from the ends of member 43. A downwardly extending stem portion 76 which is adjustably secured to the hollow movable contact 21 is attached to the center of member 43. The side operating rods 44 are secured to a movable blast valve actuator 79. The movable contact 21 makes separable engagement with the stationary hollow contact structure 22 which is fixedly supported upwardly from a base support 83. During circuit interruption an exhaust flow of arc extinguishing gas at high pressure occurs, in opposite directions, through the interior of both the movable contact 21 and the stationary hollow contact 22.

There is provided a primary blast valve 88 constituted by the lower tip portion 77 of the movable contact 21 making abutting engagement with the relative stationary primary blast valve seat 89. The primary blast valve seat 89 is resiliently supported upon the stationary contact support 83, as shown in FIG. 3. A compression spring 91 provides the desired contact pressure therebetween, and also provides for a limited amount of over-travel of the movable contact 21. Additionally, there is provided a plurality of circumferentially disposed stationary contact fingers 93 which make contacting engagement with the external side of the movable tubular contact 21.

In addition to the primary blast valve 88 there is provided a mechanically operated main blast valve 49 and a gas operated blast valve 50, which is the subject of the present invention and which will be described in greater detail hereinafter. Depending upon the voltage range and current being interrupted, the interrupter 15 is adaptable to accommodate multiple sets of coctact assemblies 20. FIG. 3 illustrates an arrangement in which only a single pair of separable contacts 21 and 22 are provided. However, for the higher voltage ratings where double break is desired a construction as shown in FIG. 4 may be used. With reference to FIG. 4 it will be observed that there is provided a pair of serially related assemblies 20. For each contact assembly, during circuit interruption, there is double flow; that is the arc extinguishing gases flow through both the stationary contact 22 and the movable contact 21.

The dual-acting piston 108 of the circuit interrupter 15 is used to open and close the contact assembly 20. The movable contact 21 of the interrupter 15 forms a seal with mating stationary contact 22 constituting a primary blast valve 88. When the breaker contact assembly 20 is closed, the seal between the tip 77 and the seat 89 at the primary blast, valve 88 prevents the high pressure gas from flowing into the interior of both of the separable contacts. When the primary blast valve 88 is closed the main blast valve 49 and the gas operated auxiliary blast valve 50 are open. When the movable contact 21 separates from the stationary contact 22, during the circuit interruption, the blast valves 49 and 50 go closed after arc extinction to stop the exhaust gas flow into low pressure chambers 103 and 104. It should be noted that the low pressure chambers 103 and 104 can be connected directly to atmosphere so the insulating gas is exhausted external of the breaker 12. Since the movable contact can reach the open position while there is still an arc between the contacts 21 and 22, it is. necessary that blast valves 49 and 50 remain open at this time, to allow gas flow to interrupt the arc. Hence, the closing of blast valves 49 and 50 must have a travel curve which is delayed from that of the moving contact 21. The main blast valve 49 is mechanically operated from the dual acting piston 108. The blast valve activator 79 is directly connected to movable contact 21 and has the same travel as the movable contact 21. As a movable contact 21 moves from the closed position, the blast valve activator 79 starts compressing a coil compression spring 105. As the movable contact 21 moves to the open position, this compression spring 105 becomes loaded, since the opposite spring seat 106 is prevented from moving. The spring seat 106 is part of the blast valve 49 assembly and the blast valve 49 is prevented from closing by two latches 107 which are spaced apart. A lip 118 on spring loaded latch 107 engages a portion of the blast valve 49 and prevents it from closing. After the activator 79 has moved a specific distance and thereby compressed the spring 105 a protrusion 128 on the activator 79 pushes the latch 107 back, disengaging it from the blast valve 49. The blast valve 49 can then go closed with a travel curve which is delayed in relationship to the opening of the movable contacts 21. When the blast valve 49 is closed, there is some pressure on it due to the position of activator 79 compressing the spring 105, plus a differential pressure holding the blast 1 valve 49 closed due to the geometry of the face of the I bylast valve 49.

During clsoing of the circuit breaker 12, when the movable contact 21 moves into engagement with the stationary contact 22, the main blast valve 49 is opened. As the movable contact 21 moves to the closed position, the activator 79 with its rubber bumper 111 strikes the blast valve 49 and moves it to the open position. A small gas dash-pot is formed between the activator 79 and the blast valve 49 to help reduce shock. As the movable contact 21 closes, the lip 118 of the latch 107 engages a portion of the blast valve 49 and the blast valve 49 is then ready for another opening operation.

F ordouble flow interruption a gas operated auxiliary blast valve 50 operates in conjunction with mechanically operated blast valve 49 to provide gas flow into and through both the moving contact 21 and the stationary contact nozzle 22, during circuit interruption. The gas operated blast valve 50 operates without mechanical coupling to the dual acting operating piston 108 and thus avoids additional loading of the piston 108. Thus, this construction of a gas operated auxiliary blast valve allows for double flow interruption in all instances without redesign of the operating piston 108 or the addition of new mechanical parts. Operation of the gas operated auxiliary blast valve 50, as can best be understood from FIGS; 3, 5, 6 and 7, will now be described in detail. FIGS. 3 and 5 show an interrupter in which the moving contact 21 is shown in the open position and the gas operated blast valve 50 is in the closed position. FIG. 7 shows a movable contact 21 in the closed position. As long as the movable contact 21 is in the closed position, blast valves 49 and 50 are in the open positions and the contact nozzle region 60 communicates directly with the low pressure chambers 103 and 104. A first auxiliary blast valve chamber 97 communicates with the nozzle chamber 60 through the fixed area metering holes 94 and will, after transient flow ceases, be at the same pressure as the nozzle chamber 60. Under these conditions a sliding portion 48 of the auxiliary gas operated blast valve 50 will be moved to and held in the open position by the force which the high pressure gas exerts in a second auxiliary chamber 98. Chamber 98 is formed by the sliding portion 48 of blast valve 50 and a blast valve guide 47. Seals 46 effectively prevent leakage of the high pressure insulating gas from high pressure chamber 98 to low pressure areas. Chamber 98 will always be at the same pressure as the high pressure system since it communicates directly with the high pressure system through inlet 99 in the blast valve guide 47.

As moving contact 21 starts to open, spring 91 and the pressure biased moving contact follower seat 89, follow tip 77 until the projecting lip 130 of the follower assembly 131 comes into contact with the stop 132 which is-part of the finger housing 133'. Thereafter, an increasing annular opening is formed between the movable contact 21 and the stationary contact 22. High pressure gas from the surrounding reservoir rushes through this opening into the low pressure nozzle chamber 60 completing circuit interruption. This high pressure gas also flows through the fixed area metering holes 94 and into the auxiliary blast valve chamber 97. When the force produced by the gas pressure in chamber 97 plus the force of the biasing spring 134 exceeds the holding force of the high pressure gas in the chamber 98 the gas operated auxiliary blast valve 50 starts to close. The time delay from the startup motion of the moving contact 21 to the startup motion of the sliding portion 48 of blast valve 50 is determined by the area of the metering holes 94.

As the sliding portion 48 of the auxiliary blast valve 50 moves towards the closed position, its motion continues to be controlled by the metering hole 94. However, gas flow through the nozzle and over the surface of the sliding portion 48, results in additional driving force which tends to accelerate gas operated blast valve 50 towards the closed position. A barrier projection 136 on the sliding portion 48 of the auxiliary blast valve 50 delays the in-rush of high pressure gas into the chamber 97 for a predetermined portion of the time of travel of the blast valve 50. Further travel of the blast valve sliding portion 48 reduces the annular discharge area 137 between parts 48 and 138 so that the venacontracta of the flow system is shifted from the primary blast valve 88 nozzle area to area 137 and results in a rapid pressure rise in the nozzle chamber 60. The resulting rapid pressure rise in the nozzle chamber produces sudden pressure rise in chamber 97 and slams the sliding portion 48 of the blast valve 50 to the closed position as shown in FIG. 5. The gas operated auxiliary blast valve 50 is now closed and prevents high pressure gas from passing into the low pressure chamber 104. The resilient valve seat 95 provides a gas tight seal between the sliding portion 48 of blast valve part 50 and the lower arc horn 138, so that, the pressure gas system which now extends inside the stationary contact assembly 22 is prevented from leaking into the low pressure chamber 1104. Differential pressure between these two systems acting on the differential area of the sliding portion 48 of blast valve 50 inside the chamber 97 provides a holding force which contains the blast valve sliding portion 48 in the closed position.

When a condition of no differential pressure exists in the breaker 12, and the breaker contact 21 and 22 are open, such as occurs during initial filling or equalization of pressures, the biasing spring 134 provides sufficient force to close the sliding assembly 48 and maintain adequate loading on the resilient seat 95 to provide a gas tight seal between the sliding assembly 48 and the arc horn 138. When an equalization of pressures occur and the contacts 21 and 22 are in the closed circuit position the sliding assembly 48 moves to the spring biased closed position in contact with are born 138. As the gas differential pressure is restored the sliding assembly 48 moves from the spring biased closed position to the ready open position as shown in FIG. 7.

The moving contact 21 is mechanically connected to the main blast valve 49 through a cross arm activator 79, the operation of which has been described hereinbefore in detail. With the moving contact 21 in the open position the main blast valve 49 is closed and high pressure exists inside both the moving contact nozzle 21 and the stationary contact nozzle 22. As the moving contact 21 starts to close, the main blast valve 49, after a fixed delay is opened, providing a discharge path for iary blast valve sliding portion 48 starts to move toward the open position. As the auxiliary blast valve 50 moves toward the open position the resulting opening 137 provides an additional exit for discharging gas from the stationary contact 22 nozzle and the chamber 97. As the area 137 increases, the auxiliary blast valve 50 moves rapidly to its fully open position and is ready for another opening operation. A resilient cushion 96 is held in position by a suitable means, such as a retaining ring, is provided as a shock absorber for the sliding assembly 48 during its opening stroke.

The present invention provides a means for increasing the interrupting capacity of single flow interrupters by converting them into double flow interrupters. This conversion from a single flow interrupter to a double flow interrupter is accomplished without mechanically coupling to the moving contact driving mechanism and thus avoiding additional loading and without redesign or additional parts being added to the operating mechanism. This invention is especially useful for interrupters of the type shown in FIG. 4, where multiple circuit breaks are required. In the interrupter shown in F IG. 4 for example, if it was desired to have double flow interruption with prior art interrupter 15 it was necessary to have a pneumatic piston 108 which was powerful enough to operate four main blast valves 49. Utilizing the teachings of the present invention, a pneumatic piston 108 which can operate two main blast valves 49 is used, and two auxiliary gas operated blast valves 50 are used for double flow interruption at each set of contacts 20.

Since numerous changes may be made in the above described apparatus and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the foregoing descriptions and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. A compressed gas circuit interrupter comprising an enclosure, an insulating gas contained within said enclosure, a first hollow tubular contact means disposed within said enclosure, a second hollow tubular contact means disposed within said enclosure, said first hollow tubular contact means being movable into and out of engagement with said second tubular contact means, an operator means mechanically linked to said first hollow tubular contact for moving said first hollow tubular contact into and out of engagement with said second contact a first blast valve means mechanically linked to said operating means to seal off the end of said first hollow contact means after said first hollow contact means separates from said second hollow contact means, a second blast valve means to seal off the end of said second hollow contact means after said first hollow contact means separates from said second hollow contact, said second blast valve means being pressure sensitive so as to close off the end of said second hollow contact means when the gas pressure within said second hollow contact means is equal to the gas pressure surrounding said second tubular hollow contact means.

2. A compressed gas type circuit interrupter as claimed in claim 1 wherein said insulating gas comprises a gas compressed to a high pressure and a gas compressed to a low pressure.

3. A compressed gas type circuit interrupter as claimed in claim 1 wherein said insulating gas comprises a gas compressed to a high pressure and means for venting said gas to atmosphere during circuit interruption.

4. A compressed gas type circuit interrupter as claimed in claim 2 wherein when said first hollow contact means engages said second hollow contact means said high-pressure insulating gas surrounds the outer surfaces of said first contact means and said second contact means, and where said low pressure gas is present inside of said first hollow tubular contact and said second hollow tubular contact, whereby when said first hollow tubular contact is separated from said second hollow tubular contact, said high pressure gas surrounding the outside of said first contact means and said second contact means rushing to the inside of and through said first contact and said second contact means.

5. The combination as claimed in claim 2, wherein the force to operate said second blast valve is derived from the differential in pressure of the said high pressure gas and said low pressure gas acting on said second blast valve means.

6. A compressed gas circuit interrupter as claimed in claim 4 wherein said first movable contact means is in engagement with said second contact means, said high pressure gas which surrounds said second hollow tubular contact means acts on said second blast valve means to hold said second blast valve means in the fully open position.

7. The combination as claimed in claim 4, wherein when said first contact means separates from the said second contact means said high pressure gas flows internal of said second contact means forcing said second blast valve means to the closed position.

8. A compressed gas type circuit interrupter as claimed in claim 7 wherein said second contact means comprises at least one fixed area metering hole, said high pressure gas flowing through said metering hole to operate said second blast valve means, so that the closing time of said second blast valve means is determined by the area of said fixed area metering hole.

9. A compressed gas type circuit interrupter as claimed in claim 5 including a spring biasing means to hold said second blast valve in the closed position when there is no differential pressure in pressure between said high pressure gas and said low pressure gas, said second blast valve constructed so that the pressure of said high pressure gas can be increased with said first contact in engagement with said second contact, and said second blast valve constructed so that the pressure of said high pressure gas can be increased when said first contact is out of engagement with said second contact. 

1. A compressed gas circuit interrupter comprising an enclosure, an insulating gas contained within said enclosure, a first hollow tubular contact means disposed within said enclosure, a second hollow tubular contact means disposed within said enclosure, said first hollow tubular contact means being movable into and out of engagement with said second tubular contact means, an operator means mechanically linked to said first hollow tubular contact for moving said first hollow tubular contact into and out of engagement with said second contact a first blast valve means mechanically linked to said operating means to seal off the end of said first hollow contact means after said first hollow contact means separates from said second hollow contact means, a second blast valve means to seal off the end of said second hollow contact means after said first hollow contact means separates from said second hollow contact, said second blast valve means being pressure sensitive so as to close off the end of said second hollow contact means when the gas pressure within said second hollow contact means is equal to the gas pressure surrounding said second tubular hollow contact means.
 2. A compressed gas type circuit interrupter as claimed in claim 1 wherein said insulating gas comprises a gas compressed to a high pressure and a gas compressed to a low pressure.
 3. A compressed gas type circuit interrupter as claimed in claim 1 wherein said insulating gas comprises a gas compressed to a high pressure and means for venting said gas to atmosphere during circuit interruption.
 4. A compressed gas type circuit interrupter as claimed in claim 2 wherein when said first hollow contact means engages said second hollow contact means said high pressure insulating gas surrounds the outer surfaces of said first contact means and said second contact means, and where said low pressure gas is present inside of said first hollow tubular contact and said second hollow tubular contact, whereby when said first hollow tubular contact is separated from said second hollow tubular contact, said high pressure gas surrounding the outside of said first contact means and said second contact means rushing to the inside of and through said first contact and said second contact means.
 5. The combination as claimed in claim 2, wherein the force to operate said second blast valve is derived from the differential in pressure of the said high pressure gas and said low pressure gas acting on said second blast valve means.
 6. A compressed gas circuit interrupter as claimed in claim 4 wherein said first movable contact means is in engagement with said second contact means, said high pressure gas which surrounds said second hollow tubular contact means acts on said second blast valve means to hold said second blast valve means in the fully open position.
 7. The combination as claimed in claim 4, wherein when said first contact means separates from the said second contact means said high pressure gas flows internal of said second contact means forcing said second blast valve means to the closed position.
 8. A compressed gas type circuit interrupter as claimed in claim 7 wherein said second contact means comprises at least one fixed area metering hole, said high pressure gas flowing through said metering hole to operate said second blast valve means, so that the closing time of said second blast valve means is determined by the area of said fixed area metering hole.
 9. A compressed gas type circuit interrupter as claimed in claim 5 including a spring biasing means to hold said second blast valve in the closed position when there is no differential pressure in pressure between said high pressure gas and said low pressure gas, said second blast valve constructed so that the pressure of said high pressure gas can be increased with said first contact in engagement with said second contact, and said second blast valve constructed so that the pressure of said high pressure gas can be increased when said first contact is out of engagement with said second contact. 